1. Statement of the Technical Field
The inventive arrangements relate to communication systems, and more particularly to systems and method for providing Time Division Multiple Access (TDMA) voice communication and/or eXtended TDMA (XTDMA) voice communication.
2. Description of the Related Art
Conventional communication systems typically comprise a plurality of Mobile Terminals (MTs) communicatively coupled to each other via Base Stations (BSs) and a network. During operations, a first MT generates a voice message which is to be communicated to a second MT. The voice message is encoded using an Error Detection (ED) code. The coded voice message is transmitted from the first MT to a BS during pre-defined time slots of a signal. The pre-defined time slots will be referred to below as time slots A1, . . . , AN. Each time slot A1, . . . , AN includes a plurality of frames of coded message data. Each frame includes a plurality of sub-frames. For purposes of ease of discussion, it is assumed that each time slot included four (4) frames F1, . . . , F4 of coded voice message data, and that each frames includes four (4) sub-frames f1, . . . , f4. Each sub-frame f1, . . . , f4 includes payload data encapsulated between trailers and headers. The payload data includes a plurality of information bits defining at least a portion of the coded voice message.
At the BS, the coded message data of each frame F1, . . . , F4 of a time slot (e.g., time slot A1) is processed to determine if errors exist therein. This processing can involve performing a conventional Automatic Repeat Request (ARQ) error control technique. One conventional ARQ error control technique generally involves decoding the coded message data of each frame F1, . . . , F4 of the time slot (e.g., time slot A1). Thereafter, a determination is made as to whether errors exit in the decoded message data.
If errors do not exist in the decoded message data, then the BS sends to the first MT an acknowledgment message indicating that the message data contained in the four (4) frames F1, . . . , F4 of the time slot (e.g., time slot A1) is error free. The BS also forwards the four (4) frames of data F1, . . . , F4 to the second MT during a particular time slot of the signal (e.g., time slot A1).
If errors do exist in the decoded message data, then the BS either discards the decoded message data (i.e., no message data is sent from BS in time slot A1) or temporally stores the decoded message data for later user in a data combining process. The BS also sends a request for retransmission of the message data from the first MT. In response to the request, the first MT retransmits the message data during a next pre-defined time slot (e.g., time slot A2) to the BS. Upon receipt of the retransmitted message data, the BS performs the ARQ error control technique using the retransmitted message data. Notably, if the BS determines that errors do not exist in the retransmitted message data, then the BS will perform either (A) or (B):
(A) send the retransmitted message data to second MT during a particular time slot of the signal (e.g., time slot A2); or
(B) combine the retransmitted message data with the temporarily stored message data containing errors, and then communicate the combined message data to the second MT during the particular time slot of the signal (e.g., time slot A2).
As a consequence of the error correction operations, a gap in the voice message is introduced by the BS. The gap in the voice message can be equal to the duration of a time slot (as shown in FIG. 13) or a multiple of the duration of a time slot. This gap degrades voice quality.